The most common form of fuel delivery system for a vehicle is systems which deliver a single fuel to the vehicle engine, such as petrol or gasoline, diesel or LPG. In more recent times, systems have been proposed for delivering alternatively petrol and LPG. Thus, these systems usually have some sort of switch over mechanism so that the vehicle engine can run only on petrol and then can be switched so that the vehicle engine runs only on LPG.
International Patent Applications PCT/AU02/00453 and PCT/AU03/000971 disclose systems in which a primary fuel such as diesel and a secondary fuel such as LPG are concurrently fed to the vehicle engine.
The nature of fuels which are available for delivery to engines and the way in which they are delivered presents specific problems which need to be addressed when designing the fuel delivery system.